GuicedEE MicroProfile Config

MicroProfile Config implementation for GuicedEE applications using SmallRye Config and Google Guice. Inject configuration values with @ConfigProperty, resolve from environment variables, system properties, and META-INF/microprofile-config.properties — all wired automatically through SPI discovery and Guice bindings.

Built on SmallRye Config · MicroProfile Config · Google Guice · Vert.x · JPMS module com.guicedee.microprofile.config · Java 25+

📦 Installation

<dependency>
  <groupId>com.guicedee.microprofile</groupId>
  <artifactId>config</artifactId>
</dependency>

Gradle (Kotlin DSL)

implementation("com.guicedee.microprofile:config:2.0.0-SNAPSHOT")

✨ Features

• CDI-style injection — @ConfigProperty(name = "key") with automatic type conversion for String, Boolean, Integer, Long, Double, Float, and Optional<T> wrappers
• Standards-compliant — implements org.eclipse.microprofile.config APIs and annotations via SmallRye Config
• Deterministic source ordering — environment variables (highest), system properties, and classpath META-INF/microprofile-config.properties (lowest)
• Custom converters — register Converter<T> implementations via ServiceLoader for application-specific types
• Profile support — profile-specific properties (e.g. %dev.key=value) resolved by SmallRye Config
• Guice-native — SmallRyeConfig is bound as a singleton via SmallRyeConfigProvider; @ConfigProperty fields are scanned and bound at startup
• Vert.x-aware initialization — config is built on a Vert.x worker thread to avoid blocking the event loop
• JPMS-ready — named module with proper exports, provides, and opens directives

🚀 Quick Start

Step 1 — Add a microprofile-config.properties file:

# src/main/resources/META-INF/microprofile-config.properties
messaging.enabled=true
messaging.bootstrap.servers=localhost:9092
liveness.port=8081

Step 2 — Inject configuration values:

import org.eclipse.microprofile.config.inject.ConfigProperty;

public class MessagingService {

    @ConfigProperty(name = "messaging.enabled", defaultValue = "true")
    boolean enabled;
    
    @ConfigProperty(name = "messaging.bootstrap.servers")
    String bootstrapServers;

    public void start() {
        if (enabled) {
            // use bootstrapServers
        }
    }
}

Step 3 — Register via JPMS:

module my.app {
    requires com.guicedee.microprofile.config;
}

The MicroProfileConfigContext initializes SmallRye Config automatically during IGuicePreStartup, and MicroProfileConfigBinder scans for all @ConfigProperty fields and binds them into Guice.

📐 Architecture

IGuiceContext.instance()
 └─ IGuiceConfigurator hooks
     └─ ScanConfig                          (enables field, annotation, classpath scanning)
 └─ IGuicePreStartup hooks
     └─ MicroProfileConfigContext           (builds SmallRyeConfig on Vert.x worker thread)
         ├─ addDefaultSources()             (env vars, system props, microprofile-config.properties)
         ├─ addDiscoveredSources()           (ServiceLoader-discovered ConfigSource SPIs)
         ├─ addDiscoveredConverters()        (ServiceLoader-discovered Converter<T> SPIs)
         └─ addDiscoveredInterceptors()      (ConfigSourceInterceptor SPIs)
 └─ IGuiceModule hooks
     └─ MicroProfileConfigBinder            (Guice AbstractModule)
         ├─ bind SmallRyeConfig via SmallRyeConfigProvider (singleton)
         ├─ scan @ConfigProperty fields via ClassGraph
         └─ bind each field type: String, Boolean, Integer, Long, Double, Float, Optional<T>
 └─ InjectionPointProvider
     └─ InjectionPointProvision             (registers @ConfigProperty as a Guice injection point)

⚙️ Configuration Sources and Resolution

MicroProfile Config defines a composite of sources with numeric ordinals. Higher ordinal wins when keys overlap:

Source	Ordinal	Example
Environment variables	300	MESSAGING_ENABLED=true
System properties	200	-Dmessaging.enabled=true
META-INF/microprofile-config.properties	100	messaging.enabled=true

Key mapping

Environment variable names follow MicroProfile Config rules:

• Dots (.) and hyphens (-) are replaced with underscores (_)
• Names are uppercased
• e.g. messaging.bootstrap.servers → MESSAGING_BOOTSTRAP_SERVERS

Profiles

SmallRye Config supports profile-specific properties using the %profile. prefix:

# META-INF/microprofile-config.properties
db.url=jdbc:postgresql://prod-host:5432/mydb

# Profile-specific override
%dev.db.url=jdbc:postgresql://localhost:5432/mydb

Activate a profile with mp.config.profile=dev (system property or environment variable).

🔄 Programmatic Access

Inject the SmallRyeConfig instance directly for programmatic lookups:

import jakarta.inject.Inject;
import io.smallrye.config.SmallRyeConfig;

public class HealthProbe {

    @Inject
    SmallRyeConfig config;

    public int livenessPort() {
        return config.getOptionalValue("liveness.port", Integer.class).orElse(8081);
    }
}

Or use the standard MicroProfile Config interface:

import org.eclipse.microprofile.config.Config;
import org.eclipse.microprofile.config.ConfigProvider;

Config config = ConfigProvider.getConfig();
String value = config.getValue("messaging.enabled", String.class);

🔌 Supported Injection Types

MicroProfileConfigBinder scans all classes with @ConfigProperty-annotated fields and creates Guice bindings for each:

Field type	Binding
String	Direct value from config
boolean / Boolean	Parsed via Boolean.parseBoolean()
int / Integer	Parsed via Integer.parseInt()
long / Long	Parsed via Long.parseLong()
double / Double	Parsed via Double.parseDouble()
float / Float	Parsed via Float.parseFloat()
Optional<String>	Wrapped optional
Optional<Boolean>	Wrapped optional
Optional<Integer>	Wrapped optional
Optional<Long>	Wrapped optional
Optional<Double>	Wrapped optional
Optional<Float>	Wrapped optional

Default values are supported via @ConfigProperty(defaultValue = "...").

🧩 Custom Converters

Register custom Converter<T> implementations via ServiceLoader for application-specific types:

import org.eclipse.microprofile.config.spi.Converter;
import java.time.Duration;

public class DurationConverter implements Converter<Duration> {

    @Override
    public Duration convert(String value) {
        if (value.endsWith("ms")) return Duration.ofMillis(Long.parseLong(value.replace("ms", "")));
        if (value.endsWith("s")) return Duration.ofSeconds(Long.parseLong(value.replace("s", "")));
        throw new IllegalArgumentException("Unsupported duration format: " + value);
    }
}

Register via META-INF/services/org.eclipse.microprofile.config.spi.Converter:

com.example.DurationConverter

And then with JPMS:

module my.app {
    provides org.eclipse.microprofile.config.spi.Converter
        with com.example.DurationConverter;
}

🔧 SPI Extension Points

All SPIs are discovered via ServiceLoader. Register implementations with JPMS provides...with or META-INF/services.

SPI	Purpose
IGuicePreStartup	MicroProfileConfigContext — builds the SmallRyeConfig instance
IGuiceModule	MicroProfileConfigBinder — scans @ConfigProperty fields and binds to Guice
IGuiceConfigurator	ScanConfig — enables classpath, annotation, and field scanning
InjectionPointProvider	InjectionPointProvision — registers @ConfigProperty as an injection point
ConfigSource (MicroProfile)	Add custom config sources with custom ordinals
Converter<T> (MicroProfile)	Register custom type converters
ConfigSourceInterceptor (SmallRye)	Intercept and transform config values

🗺️ Module Graph

com.guicedee.microprofile.config
 ├── io.smallrye.config.core          (SmallRye Config — MicroProfile Config implementation)
 ├── com.guicedee.vertx               (Vert.x lifecycle — worker thread initialization)
 ├── com.guicedee.client              (GuicedEE client — SPI contracts, IGuiceContext)
 └── com.google.guice                 (Guice DI — injection bindings)

🏗️ Key Classes

Class	Package	Role
MicroProfileConfigContext	config	IGuicePreStartup — builds SmallRyeConfig on a Vert.x worker thread at startup
MicroProfileConfigBinder	implementations	IGuiceModule — scans @ConfigProperty fields and creates Guice bindings per type
SmallRyeConfigProvider	implementations	Guice Provider<SmallRyeConfig> — returns the shared config instance
InjectionPointProvision	implementations	InjectionPointProvider — registers @ConfigProperty for Guice injection point processing
ScanConfig	implementations	IGuiceConfigurator — enables classpath, annotation, and field scanning

🧩 JPMS

Module name: com.guicedee.microprofile.config

The module:

• exports com.guicedee.microprofile.config
• requires transitive io.smallrye.config.core, com.guicedee.vertx
• provides IGuicePreStartup with MicroProfileConfigContext
• provides IGuiceModule with MicroProfileConfigBinder
• provides InjectionPointProvider with InjectionPointProvision
• provides IGuiceConfigurator with ScanConfig
• opens com.guicedee.microprofile.config.implementations to com.google.guice

In non-JPMS environments, META-INF/services discovery still works.

🧪 Testing

import com.guicedee.client.IGuiceContext;
import com.google.inject.Injector;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.*;

class ConfigTest {

    @Test
    void configPropertyFieldsAreInjected() {
        Injector injector = IGuiceContext.getContext().inject();
        MyConfigBean bean = injector.getInstance(MyConfigBean.class);
        assertNotNull(bean.getServerHost());
    }
}

Provide test configuration in src/test/resources/META-INF/microprofile-config.properties:

server.host=localhost
server.port=8080

🤝 Contributing

Issues and pull requests are welcome — please add tests for new type converters, config sources, or binding changes.

📄 License

Apache 2.0